Resistance variable element, semiconductor device including it and manufacturing methods therefor

Abstract

A resistance variable element includes a first electrode, a second electrode and an ion conductor layer interposed between the first and second electrodes. Metal ions supplied from the first electrode into the ion conductor layer accept electrons from the second electrode and are turned into metal. The so formed metal is precipitated to cross-link and interconnect the first and second electrodes to provide for voltage variations. The ion conductor layer has a stacked layer structure comprised of a first ion conductor layer formed by a compound containing oxygen and carbon and a second ion conductor layer formed by a metal oxide. The metal oxide that forms the second ion conductor layer includes at least one out of zirconium oxide and hafnium oxide.

What is claimed is: 
     
         1 . A resistance variable element, comprising a first electrode, a second electrode and an ion conductor layer interposed between the first and second electrodes;
 metal ions supplied from the first electrode into the ion conductor layer accepting electrons from the second electrode and being turned into metal which is precipitated; the metal cross-linking and interconnecting the first and second electrodes to provide for variations in resistance of the element; wherein,   the ion conductor layer is a stacked layer structure made up by a first ion conductor layer formed by a compound containing oxygen and carbon and a second ion conductor layer formed of metal oxide;   the metal oxide that forms the second ion conductor layer containing at least one out of zirconium oxide and hafnium oxide.   
     
     
         2 . The resistance variable element according to  claim 1 , wherein,
 the second ion conductor layer further contains aluminum oxide.   
     
     
         3 . The resistance variable element according to  claim 1 , wherein,
 the second ion conductor layer is one selected from the group consisting of a layered product of titanium oxide and zirconium oxide, a mixed product of titanium oxide and zirconium oxide, a layered product of titanium oxide and hafnium oxide, a mixed product of titanium oxide and hafnium oxide, a layered product of hafnium oxide and zirconium oxide, a mixed product of hafnium oxide and zirconium oxide, a layered product of hafnium oxide and aluminum oxide, a mixed product of hafnium oxide and aluminum oxide, a layered product of zirconium oxide and aluminum oxide and a mixed product of zirconium oxide, and aluminum oxide.   
     
     
         4 . The resistance variable element according to  claim 1 , wherein,
 the second ion conductor layer has a film thickness of 0.5 nm or more to 3 nm or less.   
     
     
         5 . A resistance variable element, comprising
 optional two of the resistance variable elements according to  claim 1  arrayed side-by-side; the first electrodes of the two resistance variable elements being formed as one electrode, or the second electrodes of the two resistance variable elements being formed as one electrode to provide a three terminal structure.   
     
     
         6 . The resistance variable element according to  claim 1 , wherein,
 the first ion conductor layer is formed by a polymer film having a specific inductive capacity of 2.1 or higher to 3.0 or lower and mainly composed at least of silicon, oxygen and carbon.   
     
     
         7 . A semiconductor device, comprising a multi-layered copper wiring on a semiconductor substrate thereof and the resistance variable element as stated in  claim 1 , the resistance variable element being disposed in an inner side of the multi-layered copper wiring, wherein,
 the multi-layered copper wiring includes at least a copper wire(s) and a copper plug;   the resistance variable element being made up of an upper electrode as a second electrode, a lower electrode(s) as a first electrode and an ion conductor layer interposed in-between the upper electrode and the lower electrode(s);   the copper wire(s) being simultaneously used as the lower electrode(s); a barrier insulating film being formed on top of the copper wire(s);   the barrier insulating film being formed of silicon nitride;   an opening part that reaches the copper wire(s) being formed in the barrier insulating film;   the ion conductor layer and the upper electrode of the resistance variable element being sequentially embedded only in the opening part;   the upper electrode being formed of ruthenium;   the upper electrode being connected via a barrier metal to the copper plug;   the ion conductor layer being made up of a first ion conductor layer contacted with the copper wire(s) and a second ion conductor layer contacted with the upper electrode;   the first ion conductor layer being formed by a polymer film, having a specific inductive capacity of 2.1 or higher to 3.0 or lower, and mainly composed at least of silicon, oxygen and carbon.   
     
     
         8 . A semiconductor device, comprising a multi-layered copper wiring on a semiconductor substrate thereof and the resistance variable element as stated in  claim 5 , the resistance variable element being disposed in an inner side of the multi-layered copper wiring, wherein,
 the multi-layered copper wiring includes at least a copper wire(s) and a copper plug;   the resistance variable element being made up of two of lower electrodes as the first electrode, an upper electrode as the second electrode, and an ion conductor layer interposed in-between the upper electrode and the lower electrodes;   the copper wires being simultaneously used as two of the lower electrodes; a barrier insulating film being formed on top of the copper wires;   the barrier insulating film being formed of silicon nitride;   the barrier insulating film including a single opening part that reaches the copper wires which are both of the two lower electrodes;   the ion conductor layer and the upper electrode being sequentially embedded only in the opening part;   the upper electrode being formed of ruthenium;   the upper electrode being connected via a barrier metal to the copper plug;   the ion conductor layer being made up of a first ion conductor layer contacted with the copper wire(s) and a second ion conductor layer contacted with the upper electrode;   the first ion conductor layer being formed by a polymer film, having a specific inductive capacity of 2.1 or higher to 3.0 or lower, and mainly composed at least of silicon, oxygen and carbon.   
     
     
         9 . A method for manufacturing a resistance variable element including a first electrode, a second electrode and an ion conductor layer interposed between the first and second electrodes; the ion conductor layer being a stacked layer structure of a first ion conductor layer formed by a compound containing oxygen and carbon and a second ion conductor layer formed of metal oxide; the method comprising:
 forming at least one first electrode on the surface of a silicon substrate;   forming a metal layer containing at least one metal out of zirconium and hafnium on the silicon substrate; and   forming the first ion conductor layer formed by a compound containing oxygen and carbon on the metal layer in an oxidizing atmosphere;   the metal layer being simultaneously oxidized in the step of forming the first ion conductor layer in the oxidizing atmosphere to form the second ion conductor layer.   
     
     
         10 . A method for manufacturing a semiconductor device including a multi-layered copper wiring arranged on a semiconductor substrate and the resistance variable element as stated in  claim 1 ; the resistance variable element being disposed in an inner side of the multi-layered copper wiring; the multi-layered copper wiring of the semiconductor device including at least one copper wire; the method comprising:
 forming a barrier insulating film on at least one copper wire that is used simultaneously as a lower electrode;   forming, in the barrier insulating film, an opening part that reaches the at least one copper wire;   forming, on the at least one copper wire in at least the opening part, a metal layer containing at least one metal out of zirconium and hafnium; and   forming a first ion conductor layer, formed by a compound containing oxygen and carbon, on the metal layer in an oxidizing atmosphere;   the metal layer being oxidized simultaneously in the forming the first ion conductor layer in the oxidizing atmosphere to form a second ion conductor layer.